Electronic devices (for example, optical devices such as a firearm scope, spotting scope, binocular, telescope, etc.) with sensors and/or projected digital information (for example, reticles, windage/elevation data, temperature/humidity/atmospheric pressure data, etc.) need a constant source of power from a power system (for example, a power pack) with a sufficient life to allow meaningful use of the electronic device without the need to recharge or swap the power system frequently. Once power levels in the power system fall below a defined threshold, the electronic device should integrate with the power system to allow the device to shutdown proactively without data loss. Power packs should also be simple to recharge without special equipment and easy to replace if necessary. Convenient size, weight, and mounting methods are also important considerations in power systems for electronic devices.